Allow me to share one of my low points in the game to show why this is a bad thing, not from an advantage point, but a disadvantage. I took my BLM into Castrum Abania blind when I was doing MSQ. You get to the second boss who's suddenly all "ha ha ha I'm reflecting your fire/ice/lightning spells. You know, BLM, everything you have in your kit." I panicked a little so it took me a bit to realize there were battle-specific buffs involved and that's what the game meant with the reflect thing. Imagine them expanding that to your actual kit. And lbh, you can't have a system where classes have advantages without also active disadvantages, and no one wants that.